(a) Field of the Invention
The present invention relates to a differential pinion gear having an abrasion-preventing interior surface.
(b) Description of the Related Art
Typically, a differential gear transmits driving torque from a transmission to an axle. The differential gear achieves smooth driving without fatiguing the wheels by regulating rotation speeds of the wheels.
A typical differential gear includes a drive gear, which receives torque from the transmission, and a differential case bolted to the drive gear. A pinion shaft is inserted to the differential case and a pair of pinion gears are rotatably engaged to the pinion shaft. A pair of side gears is coupled between the pinion gears and the axle such that the side gears transmit power from the pinion gear to the axle. The pinion gear and the pinion shaft need high contact fatigue strength and anti-abrasion properties to transmit the engine torque to the wheels.
Further, lubricant is provided on interior surface of the pinion gear. The lubricant may leak in the axial direction. Abrasion thus occurs to the pinion shaft, and if the abrasion is serious, adhesion may occur.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.